It is known to make fibers, fibrils, filaments, and openwork or reticulate fibrillated strands of high-polymer synthetic resins and mixtures thereof. The various organic and/or inorganic compounds are converted by casting, spinning, stretching, stretch-tearing, cutting, splicing, and joining into the desired form. East German Pat. No. 137,951 describes a method that forms a textile strand out of a mass of powder of a thermoplastic high-polymer resin. This mass is heated and treated to form the desired structure.
Fibrillated textiles, known and preferred over many synthetic-resin textiles for their nice look and hand, are constituted of fibrils which are morphologically overmolecular units that have diameters from 0.05 micron to 10 micron and lengths from 100 microns to several millimeters long. The fibrils normally extend parallel to the goods. This effect is achieved by the tendency of melt-spun polymer mixtures of polyethylene terephthalate, polyamides, polystyrene, and polyolefins to split, as discussed in U.S. Pat. No. 3,819,769. It is also known to position the fiber-forming polymer in a matrix and to dissolve out this matrix before, during, or after treating it. Such a method is inherently discontinuous, and consumes considerable quantities of valuable solvents.
More particularly, West German Pat. No. 2,040,802 describes a method of making compound filaments by imbedding polyethylene terephthalate fibrils in a polystyrene matrix. After dissolution of the matric fibers are obtained of a fineness of 0.1 dtex and a diameter of 4 micron. West German Pat. Nos. 1,949,170 and 2,063,440 describe mixtures of polyamides and polyethylene terephthalate including the matrix-fibril structure formed thereby. East German Pat. Nos. 128,965 and 84,061 describe methods of splicing together fibrillable foils.
A disadvantage of all of the known processes is that the fibrillability is only obtained using mixtures of normally incompatible polymers that are forced together under pressure. In addition it is necessary to use subsequent treatments, such as chemical dissolving or mechanical splicing, to complete the procedures.